There is known an image forming apparatus including a fan in a housing. In the image forming apparatus, when a fan is driven, the air on the outside flows into the housing.
The image forming apparatus is sometimes used in an environment with a lot of dust or dirt (hereinafter collectively referred to as “dust”). In this case, a lot of dust intrudes into the image forming apparatus together with the air.
In general, as measures against dust, it is known to provide a filter for dust collection. However, if the image forming apparatus is used in the environment with a lot of dust, an amount of dust accumulating in the filter increases. Therefore, it is likely that a frequency of replacement of the filter increases. Further, clogging sometimes occurs in the filter. If the clogging occurs in the filter, it is likely that a flow of the air in the housing is deteriorated.